Variable-pitch propeller



1,589,174 S. HEATH VARIABLE FITCH PROPELLER Filed August l0, 1921 3 Sheets-Sheet l 47 Z l L46 /6'3 June l5 1926.

June 15, 1926. 1,589,174

. S. HEATH VARIABLE FITCH PROPELLER Filed August l0, 1921 3 Sheets-Sheet 2 SH01 mugs June 15,1926. 1,589,174

S. HEATH VARIABLE PI TCH PROPELLER Filed August 10, 1921 3 Sheets-Sheet ."5 we?.

attorney, 5p

Pue-md 15, 192s.

luNl'lflazD s'rA'rEs PATENT OFFICE.

SPENCER HEATH,`OF ELKRIDGE, MARYLAND.

VARIABLE-FITCH PROPELER.

Application nea August 1o, 1921. sei-rai no. 491,202.

This invention relates to variable pitch `:propellers and more particularly to propellers employed in connection with airplanes, and airships.

""It has heretofore been proposed to so construct and monntcthe propeller blades that they may be rotated upon their own axes in order to adjust their angular relation to the plane of rotation of the propeller. Such angular adjustment is desirable to compensate for variationsV in the density of the air at dierent altitudes, and particularly for reversing the pitch of the blades when landing, in order to bring the machine to a 'tle of the' motor when the angu ar 'closing of the throttle quick stop.x l t Whenuslngpropellers of this character, however,- it has been .found in practice-that it is diicult for the operator to `ascertain or determine theez'rtentl of 'the angular adjustment or displacement of the blades when he operates theadjusting means, since the propellersare revolving at a highrate of. speed and the blades are invisible. He can 'only judge ofthe vdegree of adjustment by the results produced, and this method bf control is obviously more. or less uncertain.

It is therefore an object of the present in- I ventiomtoprovide means for accurately indicating to the operator,'the.exact angular position of the blades at all times', so that he may be able tomake the necessary adjustments intelligently.

In the useof variable itch propellers,it has been found that as the angle increases, the resistance also increases,and consequently more power is required-to drivethe propeller. This necessitates openin the throtposition of' the blades is increased.` Likewise as the blades approach the plane of' rotation of the propeller, the resist-ance becomes ,less and the motor has a tendency to race, unless the throttle is closed. This opening an has heretofore been done manually, as occasion required, 'but it is an object of the present invention to provide means for automatically opening and closing the throttle or .otherwise varying ,the in accor ance power of thel driving motor, with the angularv position "of the blades. Thus the operator isrelieved ef. the necessity of manipulating the throttle as the blades are adjusted.,

In order that the invention may be readily understood, reference is had to the acblades 6 and these may be companyin drawings illustrating one -embodiment -ereef,.'and forming part 'of this specification, in which drawings;

y Fig. '1 's a view partially in elevation and partially in section, showingrmy'improved variable pitch propeller, with its cont-rol mechanism, andalsoillustrating part of the indicating and motor control gear.

' Fig..2 1s a side elevation of my improved pi'opeller` hub. and control mechanism, arts` ing broken awa and the housing ing omitted for the sa e of clearness, this view belng taken on a plane at right-angles to that of Fig. 1.

Fig. Sis a transverse `section substantially on the line with 3-3 of Fig. 1l looking in Ithe direction of the arrow- Fig. 4jis a lon itudinal section through Referring to. the drawings in detail, l designates the `propeller hub having a central portion 2 provided with a tapered bore to receive'the tapered end of the power shaft 3 which drives the propeller, the hub'being secured vto this shaft by means of lock nuts 3.

5 designates the Shanks of the propeller secured in the hub in any suitablemanner. As shown, the Shanks are set in metal 4ferrules 7 mounted d for rotation in the hub socketsand held in place by means of retaining rings' 8.

Atthe inner ends of the blade Shanks are secured annular internal gears 9 with vwhich mesh pinions IO and 11, mounted on shafts 12. and 13', to' which1 are also secured worm wheels 14 and 15 respectively, which mesh with a pair-of worms 1 6 and -17 Ona shaft .18. Theshaft 18 is journaled in bearings in i vthe hub and has its end projecting outside of the sa-me. On this projecting end issev cured a gear wheel 19l which meshes with a pinion 2O rigid with a gear 21, the gears and 21 being mounted for rotation on a. stub shaft carrled by a bracket 21 secured to the hub.

All of the parts above described are substantially simllar in construction and operation to the corresponding parts disclosed-in my above mentioned co-pending application, except for the gear 2l. This gear corresponds in function with the similarly numbered gear in my above mentioned application, but is of slightly different construction. In the present case, this gear 21 is shown as comprising two parallel toothed portions united by a smooth portion 21" of reduced diameter, thus in eii'ect providing a central annular groove around the gear 21. This groove is for the purpose of accommodating a gear 22 mounted on an extension 4 of the hub 1, as in the above mentioned application. While a similar gear 23, mounted concentrically with the gear. 22, meshes with one side of thev gear 21.

(3o-operating with the above described gears, is a compensating pinion or back gear which comprises a relatively large central portion 26, and a pair of smaller portions 25, arranged one on each side of the portion 26. It will be observed that the gear 22 is somewhat larger than the gear 23, and the portions and 26 of the compensating pinion are proportional in size to the gears 22 and 23. Thus for example, if the gears 23 and 22 are provided with 65 and 70 teeth respectively, the portions 25 and 26 of the compensating pinion may properly have 26 and. 28 teeth respectively. By reference to Fig. 7. it will be seen that the gear 23 meshes directly with the gear 21, while the gear 22 meshes with the portion 26 of the compensating pinion, the portions 25 thereof meshing with the gear 21, the groove 21" serving also to accommodate the portion 26. By this mea-ns it will be understood that equal angular displacements of the gears 22. and 23 produce the same angular displacement of the gears 21. The compensating pinion 25-26 is therefore simply in the nature of an idler or back-gear, and is journaled upon a stub shaft carried by a bracket 25 secured to the hub 1.

As in my former application above identiied, a pair of-brake drums 27-29 is provided for producing the angular adjustment of the blades. The brake drum 29 is preferably formed integral with the gear 23, while the drum 27 is rigidly secured to a sleeve 24 which is also rigid with the gear 22, the sleeve 24vbeing journaled upon the extension 4 of the hub and the brake drum 29 and gear 23 being in turn journled upon the sleeve 24. The drum 27 is secured in pisition by means of a suitable locking ring .Surrounding the brake drums 27 and 29 is a housing preferably formed of two halves or sections 30 and 31,' held together by means of bolts passing through suitably located holes 32. A bracket 36 extends from one side'of the housing, and between the walls of this bracket isl located a lever 37 for controlling the brakes. This lever is exactly similar in construction and operation to that shown and described in my prior application above mentioned. It comprises a T- shaped head or `end 38 carrying cross pins 39 and 40. The ends of these pins extend through and work freely in arc-shaped slots 44 and 45 formed in the walls of the bracket 36. To the pin 39 is secured one end of a brake band 41 which encircles the brake drum 29, and to the pin is secured one end of a second brake band 42 which encircles the drum 27, the other ends of these bands being anchored to the housing as indicated at 43 in Fig. 3. It will be obvious that as 4the lever 37 is swung to one side or the other, it pivots about one or the other of the pins 39 and 40 and selectively causes one or the other of the brake bands 41 and 42 to engage the respective drums 29 and 27, all as described in my above mentioned aplplication.

preferably provide a centering spring 46 y as clearly shown in Fig. 3, one end of which being secured to the lever 37 and the other end being anchored to the housing 30. The object of this spring is to return the lever 37 to its central or normal position when released, in which position both brake bands are free from their respective drums.

In order to operate my improved indicating and motor controlling mechanism, I provide the following construction. The adjacent sides of the drums 27 and 29 are bored out to receive rings or flanges carrying a pair of annular gears 34 and 35, these rings being 'preferably forced into the drums with a driving fit. The gear 35 is free to rotate with the drum 29 upon the sleeve 24, but the gear 34, with its drum 27, is' rigidly secured to the sleeve 24, as by means of screw threads 28a.

Meshing with the annular gears 34 and 35 are relatively large gears 47 and 48 mounted uponA shafts 49 and 50, journaled 1n the opposite walls' of an extension 33 of the housing 30-3l. On each shaft 49 and 59 1s also secured a relatively small gear or p1n1on 51. These pinions 5l mesh with relatively larger gears 52 mounted on shafts 53-54 journaled in the Wall of the housing. These shafts 53 and 54 are led to the indicating and controlling device situated at any suitable point, and may be either in the nature of flexible shaftsyormay be provided with suitable universal joints as indicated at 55 in Fig. 5. The indicating and controlling device consists of a casing or housing 60 in which is mounted differential gearing now to be described. The shafts 53 and 54 enter Y the casing 60 through .bearings 56, and are words, the shape of the corresponds to that ofthe end housing 60.

provided within the casing with worms 57 and 58, these worms beingsuitably supported by means o f a frame` work 59. 'The Worms 57 and .58 mesh respectively with worm wheels 61 and 62 loosely mounted upon'a shaft 68, and having rigidly u mted thereto bevel gears 63 and 64 respectively'. are both in mesh with a pair of bevel idlers y65 and 66 carried b o a spider 67, after the manner common in 1fferential gearing. This spider 67 isrigidly secured to the shaft 68 and this shaft is journaled in bearings 69 and 69* carried by 4the frame Work 59, and supported by the At the front end of the housing 60 is a dial 70, referably circular in form, and graduate as shown in Fig. 5. The reduced end 71 of the shaft 68 projects through .the center of this dial and on the projecting end tliereof is mounted -a pointer 72. Thls may be an ordinary indicating needle, but is shown as being in the nature of an aerofoi or miniature propellerblade.4 In other pointer 72 preferably of the propeller bladesuch as shown at 6 in Fig. 1.

On the dial 70 is laid off a zero line corresponding with zero pitch, or in other- I words,

the position of the propeller blades when they coincide with the plane of rotation. Alsothe dial preferably bears -another mark indicating the normal angle which the blades should ordinarily occupy, and the movement of the indicator 72 Von either side of this line shows to the operator the angular displacement of the blades from their normal pitch.

From the above described construction, 1t will'be apparent that when the propeller is running normally, free. the twogears 34 and 35 revolve with the brake drum at the same speed and con# sequently the two shafts 53 and 54 are driven at the same speed. Therefore, o wing to the differential gearing shown in Fig. 4, the shaft 68 remains stationary. When, however, the brake band is tightened on one or the other of the drums, such drum is retarded, and through the medium of the gears 22 .or 23 as the case may be,"and the trans- 'mission gearing 21, 20, 19, etc., actuates the pinions 10 and 11 and rotates the blades'` upon their own axes, as described in detail in my former ap lication. At the same ti me, this retarding o one of the drums produces a rotation or -displacementof such drum relative to the othenand this.v acting through the gears 34-35, 47-48,\ and 51-52, immediately produces a dierence i'n the speed of the shafts 53 and 54; This diEerence in' `speed'is in turn transmitted to the worm wheels 61' and 62 in Fig. 4, with the result that the shaft 68 is correspondingly displaced, and the` inter 72 with 4both brake bands over the dial. ince the shaft 68 rotates whenever the blades rotate about their axes and 'remains stationary when the blades are stationary in their soc ets, it may be termed a mimic shaft. It will be observed that the blades 6, as well as the pointer 72, will con-v tinue their angularmovement so long as one of the drums 27 or 29 is retarded, and that since it is the extent of retardation or relative shifting of these drums which produces both the adjusting of the blades and also the movement ofthe pointer, such movement will always be exactly proportional to the angular adjustment lof the blades. This exact proportionality is secured by virtue of the employment of the compensating pinion caused to travel I 25-26, above described, by means of which the angular movement of the blades is made to exactly correspond to the angula`r displacement of the drums.

It will thus be seen that the pointer 72 serves at all 'times to indicate to the ,operator the exact angular osition of the blades relative to thev plane 0F rotation of the propeller, and that by watching this pointer, the operator can intelligently make just such adjustments as occasion may demand.

In order to automatically control the power sup lied to the shaft 3 for driving the propel er, as the angle of the blades changes, I provide a suitably shaped cam 7 3l (see Fig. 6) and secure it upon the shaft 68 as showngin Fig. 4. This cam isA adapted to bear against a roller 74 carried by a push rod 75, which rod controls the power supplied to the motor. In the case of an internal combustion engine, the rod 75 preferably controls the throttle supplying motive f fuel to the engine. It will be noted that the cam 73 isso shaped and mounted as to push the rod 7 5 outward and thus close the lthrottle or shut 0E the power as the bladesy approach the position of zero pitch,

or in other words. approach the plane of rotation, and that the rod 75 is permitted to move in the other direction under the. influence .of a spring -(not shown) so as 4to increase the power or open the throttle as the angle of the blades increases.- Thus the power delivered to the propeller shaft is always maintained proportional to the resist'- ance which the propeller encounters, and the speed thereby rendered substantially constant.

@What I claim is:

f 1. The combination with a ing a blade angularly adjustable about its axis, a shaft for' drivingv said ropeller. mechanism. for adjusting saidA blade and simultaneously indicatingthe yangular positon thereof, said mechanism comprising two elements normallvmotating with said shaft but rotatable relative thereto, means for 'I causing either of' said elements torOtatik propeller hav Ail() iisd relative to the other and relative to said shaft, means affected by such relative movement between said elements for angularly adjusting the blade and means for simultaneously operating said indicatingmechanism.

2. The combination with a propeller having a blade angularly adjustable about its own axis, a shaft for driving said propeller mechanism for adjusting said blade 4and '.'simultaneously indicating the angular posi- 'tion thereof, said mechanism comprising two elements normally rotating with said shaft but rotatable relative thereto, means for retarding the rotation of either of said ele-I ments relative to the other and to said shaft, means actuated by the difference in the speed -of rotation of said elements for adjusting said blade and means for simultaneously operating said indicating mechanism.

3. The combination with a propeller having an angularly adjustable blade and a shaft on which the same is mounted, of mechanism for adjusting said blade at will, such mechanism comprising a pair of elements rotatably mounted on said shaft and normally rotating with the propeller, and means for causing rotary movement of either of said elements relative to the other element, an indicator having 'a lmovable pointer for indicating the' angular position of said blade and means affected by the relative movement between said elements for actuating said ointer.

4. The combination with a propeller having an angularly adjustable blade, of mechanism for adjusting the same at will in either direction, such mechanism compnising a pair of elements normally rotating wit the propeller, and means for selectively retarding one or the `other of said elements, an indicator for showing the angular position of said blade, and means due to the difference in the speed of rotation of said two elements .for actuating said indicator.

5. The combination with a propeller having an angularly adjustable blade, of mechanisni for adjusting the same at will, such mechanism comprising a pair of brake drums normally rotating with the propeller, a pair of brakes adapted to selectively engage said rotating drums to retard one relative to the other, and thus operate said adjusting means, an indicator for showing the angular position of said blade, and means responsive to the angularv displacement of,

one of said drums relative to the other for actuating said indicator.

6. The combination witha ing an angularly adjustable blade, and a shaft for driving said propeller, of mechanism for adjusting' said blade at will, such mechanism comprising a .pair of elements normally rotating with said shaft, said elements being rotatable relative to said shaft propeller havinseam and to each other, an indicator having a movable member for showing the angular position of said blade, and mechanical connections between said rotatable elements and the' movable member of said indicator whereby the latter is actuated by the. relative movement between the former, said connections including differential gearing.

7. The combination with a propeller having an 'angular-ly adjustable blade, of mechanism for adjusting the sameat will in either direction, such mechanism comprising a pair of elements normally rotating wit the propeller, and means for selectively retarding one or the other of said elements, a movable device for varying the amount of power driving said shaft in accordance with the angular position of said blade, and mechanical connections between said elements and said movable device whereby the latter is actuated by the difference in speed of rotation of said two elements. c 8. The combination with a propeller having an angularly adjustable blade, and a motor for driving the same, yof means for angularly adjusting such blade while the motor is running, and means for automatically controlling the supply of motive uel to said motor in accordance with the angular position of said blade, said last named means including differential mechanism responsive to the action of said adjusting means. 9L A. propeller having an angularl adjustable blade, and means for angularlyy adjusting the same, such means comprising a pair ont' brake drums normally rotating with the propeller, a pair of brakes adapted to engage said rotating drums to actnate the adjusting means, a lever for `selectively shifting said brakes into engagement with their respective drums, and a spring for normally maintaining said lever in such position as to hold the brakes out of contact. 10. A propeller having an angularly adjustable blade, and means for angularl adjusting the same, such means comprism a pair of brake drums normally the propeller, a pair of brakes adapted to engage said rotating drums to actuate the adjusting means, a lever shiftable in either direction from a central position for selectively shifting said brakes, and means for automatically returning' said lever to and yieldingly maintaining it in such central position.

lljA propeller having an angularly adjustable blade, and means for angularly adjusting the same in either direction, Such means comprising a pair of brake drums normally rotating with the propeller, a pair of brakes adapted to engage and relatively angularly displace said rotating drums to actuate the adjusting means in one direction or the other, and mechanism connecting said brake drums with said blade in such a mantid lll@

rotating with angularly displace said rotating drums to actuate the adjusting means in one direction or the other, and mechanism connecting said brake drums with said blade in such manner that the angular adjustments of the blade, in one directionor the other, are strictly proportional-to the angular displacement of the respective drums relative to the propeller shaft.

13. The combination with a propeller having an angularly adjustable blade, and a Apower shaft on which it 1s mounted, of

mechanism for ad]usting said blade at will, such mechanism comprising a pair of rotatable elements, a movable device for varying the amount of power driving said shaft in accordance with the angular position of said blade, and mechanical connections between said rotatable elements and said movable device whereby the latter is actuated b the former, said connections including di ferential gearing.

14. In a variable pitch propeller, in combination 'with a hub and ,blades adjustably journaled therein, a pair of normally rotating elements coaxial with the propeller hub, means for causing differential motion between the said pair of elements, a gear train from said elements to each journaled blade, a mimic shaft, differential gearing for operating said shaft and including two gears, and a ear train from each member of said pair o elements to one of said last named gears, and means operated by movement of said mimic shaft for indicating the angular position of the blades. f

15. In a variable pitch propeller, in combination with a hub and blades adjustably journaled therein, of a main shaft on whic said hub is mounted, a pair of normally rotating elements coaxial with the propeller hub, means for causing difierentialmotion between the said pair of elements, a gear train from said elements to each journaled blade, a mimicshaft, differential gears for rotating said shaft and including two gears, a gear train from each member of said pair of elements to one of'said last named gears,

and means operated by said mimic shaft for indicating the angular position of said blades and for varying the amount of power a driving said main shaft.'

16. In a variable pitch bination with a hub and blades adjustabl journaled therein, of a maiinshaft on which said hub is mounted and an engine for rotating the same, a pair of normally rotating elements, means for causing differential motion between said elements, a mimic shaft, means for communicating said differential motion respectively to said journaled blade and to said mimic shaft, an indicating device, an engine control device, both of said devices being operatively connected withhand propeller, in comcontrolled by the movements of said mimic shaft.

17. A propeller comprising a hub having a socket, a blade having a shank rotatable about its own axis in said socket, and means for so rotating said blade in either direction, said means comprising a pair of independent toothed a gear -w meshing with one of said gears, said gear wheel comprising two parallel toothed portions and an intermediate smooth portion of reduced diameter, an idler pinion having on each end ya toothed portion meshing with said toothed portions of said gear wheel, said pinion also having an intermediate toothed portion of large diameter than said end portions, said intermediate portion meshing with the other of said toothed gears.

18. A propeller comprising a hub having sockets, a blade mounted in each of said sockets for rotation about its own axis, and means for simultaneously rotating said blades, said means comprising a pair of in dependent toothed gears rotatable about the same axis, two gear wheels carried by said hub and mounted on opposite sides of said toothed gears, both of said gear wheels being in mesh with one of said gears, each of said gear wheels comprising two parallel toothed portions and an intermediate smooth portion of reduced diameter, an idler pinion for each of said gear wheels, each of said idler .pinions havin toothed portions at its ends meshing witlga the parallel toothed portions of one of said gear wheels, each of said idler pinions also having an enlarged intermediate toothed portion meshing with* the other of said toothed gears.

In testimony whereof I affix my signature.

SPENCER HEATH.

glears'rotatable about the same axis,

eel 

